Mountain Climbers

Posted by Katherine J. Wu

https://www.theatlantic.com/science/archive/2025/07/animal-sunscreen/683611/?utm_source=feed

For all of the eons that animal life has existed on Earth, the sun has been there too. And for all of those eons, animal life has had only one solution for intense exposure to the sun: evolution. Some creatures have thick, dark skin that’s resistant to UV harm; others sprout fur, scales, or feathers that block the sun’s rays. Many fish, reptiles, amphibians, and birds may produce a compound that protects their cells against the sun’s damaging effects. Hippos, weirdly, ooze a reddish, mucus-y liquid from their pores that absorbs light before it can destroy their skin. And plenty of creatures have evolved behaviors that take advantage of their environment—rolling around in dirt or mud, simply retreating into the shade.

But certain modern animals have sun problems that natural selection can’t easily solve. Some reside at zoos that can’t perfectly replicate their habitat; others live at latitudes that their ancestors didn’t experience. Others spend too much time sunbathing in a living-room window, or sport sparse or light-colored fur or hair because their domesticators liked the way it looked. For these animals, people have come up with a shorter-term solution: sunscreen.

If, that is, a creature is willing to accept the treatment. Indu, an Asian elephant who lived at the Phoenix Zoo, was game. A few years ago, Heather Wright, one of the zookeepers, noticed the tops of Indu’s ears pinking, peeling, and flaking in the summer heat, much like her human keepers’ did. So her caretakers picked up some zinc-oxide-based sunblock—specially formulated for sensitive (human) skin—and dabbed it on the elephant. Indu, to be fair, was used to a level of care most wild animals don’t enjoy. “We had already been applying lotion,” to manage dryness, Wright told me. The elephant knew the drill: Once in the barn, she’d lumber up to a window with an opening for her ear and stick the appendage through.

As far as zoo staff members could tell, the treatment helped. “There’s nothing magical” about other animals’ skin, Leslie Easterwood, a large-animal veterinarian at Texas A&M University, told me: Bake it in the sun, and it will burn. Scientists have spotted whales suffering from sunburns; cats, dogs, horses—even alpacas, turtles, and penguins—can develop all kinds of skin cancers. Pigs, in particular, “have skin most similar to humans,” Mitchell Song, a veterinary dermatologist based in Arizona told me. At Zoo Miami, keepers have spread mud on older, arthritic wild pigs who can’t wallow as well as they did in their youth; they’ve also applied sunscreen to a babirusa, a species of swine native to Indonesia’s forests, and to a Kunekune pig, Gwen Myers, the zoo’s chief of animal health, told me.

In some sunny places, vets commonly recommend sunscreen for pets and other domesticated creatures, especially light-colored dogs and horses. Steve Valeika, a veterinarian in North Carolina, advises the same for “white cats that go outside.” This particular conundrum is one of our own making. “You don’t see a lot of white-skinned animals in the wild,” Anthea Schick, a veterinary dermatologist in Arizona, told me. Only thanks to generations of selective breeding have they become a frequent presence in and around people’s homes.

Of course, to sunscreen your pet, you have to … sunscreen your pet. Some pet owners, vets told me, are definitely flummoxed by the suggestion: “It’s not widely discussed,” Schick told me. Vets are more unified in recommending teeth brushing for cats—and most cat owners still just decide they’d rather not. But some animals would certainly benefit from block: Schick told me she’s seen her fair share of badly burned dogs, especially after long bouts of sunbathing that scorch their bellies. “We see a lot of sun-induced skin cancers that could be avoided,” she said. Pit bulls, Dalmatians, and other short-haired breeds are especially vulnerable; even long-haired white cats are sensitive around their eyes, their nose, and the tips of their ears. And Easterwood estimates that the majority of paint horses, left unprotected, will eventually develop skin issues. Squamous-cell-carcinoma cases make up the majority of her workload: “I see it every single day,” she said.

The vets I spoke with generally agreed: Don’t bother with sprays, which a lot of animals find annoying or downright terrifying; reapply often, and well; it is way, way, way harder to sunscreen a cat than a dog, though some brave souls manage it. But although some vets recommended human sunscreens, formulated for kids or sensitive skin, others told me they preferred blends marketed for animals. (The FDA has dubbed just one pet sunscreen, made by a company called Epi-Pet and marketed to dogs and horses, “FDA compliant”—not the same as FDA approval, which requires rigorous safety testing.) Several warned against zinc oxide, which can be toxic to animals if ingested in large quantities; others felt that zinc oxide was worth the risk, unless administered to a tongue-bathing cat.

Regardless of the product they’re offered, most animals generally aren’t as eager as Indu to subject themselves to a human-led sun-protection ritual. And even she was usually plied with a five-gallon bucket of fruits and vegetables while her keepers tended her ears. At Zoo Miami, keeper Madison Chamizo told me she and her colleagues had to spend months training an okapi—an African mammal closely related to a giraffe—to accept caretakers gently scrubbing sunscreen onto her back with a modified Scotch-Brite dishwand, after she lost some patches of hair on her back to a fungal infection. But for creatures in very sunny parts of the world, the alternatives are, essentially, being cooped up indoors, kept away from windows, or wrestled into full-body sunsuits. (Some dogs don’t mind; cats, once again, are unlikely to comply.)

And some sun-related problems, sunscreen can’t fix. Gary West, the Phoenix Zoo’s vet, told me he suspects that UV glare has caused eye inflammation in some of his animals; Myers, in Miami, worries about the sensitive skin around some species’ eyes. “They’re not really going to wear sunglasses for us,” Myers told me. So she and her colleagues have started to wonder: “Gosh, is this an animal that we could put a sun visor on?”

https://www.theatlantic.com/science/archive/2025/07/animal-sunscreen/683611/?utm_source=feed